THE SPOROZOA 221 



With the formation of the sporozoites the life-cycle has been brought 

 back to its starting-point, and requires only the infection of a new 

 host. 



The sporogony takes two or three days in Ooccidium schubergi ; in C. 

 falciforme of the mouse it takes as long as four days. The clear spheres 

 mentioned above in the sporoblasts and spores can be isolated by crushing 

 the spore, and are viscid, plastic bodies which dissolve in dilute or strong 

 acids, and which, when treated with weak acetic or hydrochloric acid, 

 swell up before dissolving a property which Schaudiun believes to be 

 largely instrumental in the bursting of the spore-envelope in the gut of a 

 new host. The first effect of the digestive juices is to produce an aperture 

 in the wall of the oocyst (Fig. 51, XV). Then the sporocysts burst 

 with a distinct jerk, always along an even meridional line, which, if 

 preformed, cannot be detected beforehand. The sporozoites lie tete-beche 

 within the spore, and creep out in different directions (Fig. 54, /). 

 The oocysts, sporocysts, and residuary bodies are left behind and cast 

 out with the faeces. 



The infection of the Lithobius is always a casual one, by way of the 

 digestive tract. Sometimes a centipede becomes infected by eating another 

 of its kind ; infection then is conveyed not only by the oocysts, but by 

 all other stages except the immature, not fully -grown schizonts or 

 gametocytes, which pass out with the faeces after digestion of their host- 

 cells. Frequently the faeces of infected centipedes are eaten by wood-lice 

 (Oniscus and Porcellio). The contained oocysts then pass through the gut 

 of the wood-louse quite unaltered ; but if a wood-louse containing an 

 oocyst be eaten by a centipede, the latter will become infected. In this 

 case the wood-louse is not an intermediate host, but a simple carrier. 



It follows from the mode of infection that centipedes living in a con- 

 fined and restricted area have a much greater chance of taking the 

 infection from one another, and Schaudinn found that a very large 

 proportion of the specimens of Lithobius obtained by him from outhouses 

 in the grounds of the Zoological Institute at Berlin were infected with 

 the parasites, but that Lithobii collected in the woods and forests were 

 generally free from them. 



In moles infected by Cyclospora, Schaudinn [5 1 a] found that the 

 infection was not transmitted by cannibalism, although these pugnacious 

 animals frequently eat each other. He believes that in nature the mole 

 becomes infected by eating wood-lice and other dung-feeding Arthropods, 

 which have fed on the faeces of other infected moles. 



The variations in the morphology and development of other 

 Coccidia, as compared with the type here selected, are best con- 

 sidered under two heads : first, structural and morphological 

 variations in the individual stages of the life -history; secondly, 

 variations in the composition of the life -cycle considered as a 

 whole. 



(1) Morphology. Some of the differences between Coccidium 

 schubergi and its two colleagues, C. lacazei and Adelea ovata, have 



